Control device



June 9, 1931. C, H HQDGKlNs 1,809,299

CONTROL DEVICE Filed Dec. 13, 1927 2 Sheets-Sheet l ATTORNEY Jne 9, 1931. c. H. HoDGKlNs 1,809,299

CONTROL DEVICE Filed Dec. 13, 1921 2 sheets-sneer 2 INVENTOR mdk@ #waag/m 'ATTORNEY A Patented .im a, 1931 UNITED STATES PATENT OFFICE CHARLES H. HODGmB, OF PITTSBURGH, PENNSYLVANI, ASSIGNOB TO "W'ESTmG- HOUSE ELECTRIC! HANUFACTUBIG COMPANY, L CORPORATION OF PENNSYL- VANIA CONTROL DEVICE Application illed December 13, 1927. Serial No. 238,668.

My invention relates to control devices and partlcularly to thermal relays. l

An object of the invention is to provide a thermal relay that shall be simple in construc- 5 tion, eicient in its operation and easily manits having been actuated to a predetermined circuit-controlling position. c

For a fuller understanding of the invention, reference may be had to the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a top plan view, partially in section, of a thermal relay embodying the invention.

Fig. 2 is a view in section, taken on line 2 11-11 of Fig. 1.

Fig. 3 is a fragmentary view, partially in section, of a circuit interrupter embodied in the device of Figs. 1 and 2 in a circuit closing position, and

Fig. 4 is a view of the same device in its circuit opening position.

In the drawings, a base 1 is illustrated on which a. switch mechanism 2 is mounted. The switch mechanism comprises a stationary Contact 3, a movable contact bar 4, a contact actuating bar 5 and a latch 6 for latching the bar 5 in a predetermined position. The movable contact 4 is provided with a flexible conductor 7, that is connected to a terminal 8 mounted on the base 1. J

The movable contact bar and the contact actuating bar are loosely secured to a switch support 9, that is movable in a groove or recess 10 in the base, by means of a bolt 11.

As shown, the bolt 11 extends through the lower ends of the bars 4 and 5 and an upstanding portion 12 of the switch support 9, and is held in position by a cotter pin 13 or other suitable means. The contact-actuating bar may be spaced from the upstanding por tion 12 by a washer 14 in order that the bar may be freely movable relatively to the upstandin portion.

In order that the'switch mechanism 2 may be biased 'towards an open circuit position (see Fi 4), a coil spring 15, disposed between t eicontact bar and the head of the bolt, is provided. When the actuating bar 5 is in the osition shown in Fig. 4 of the drawings, t e spring l5' tends to move the contact bar 4 out of engagement with the stationary contact 3, but when the contact actuatlng bar 5 is moved towards the right to the position shown in Figs. 1 and 3 of the drawings, the bar 5 presses against the bar l 4 at a point 16, moving the bar 4 into engagement with the contact 3. Since the upper end of the bar 4 cannot move after it engages the contact 3, and since the bar 5 is prevented from moving to the leftby the upstanding portion 12, the contact bar 4 is caused to pivot on the contact 3 as the spring l5 is compressed. Thus, it is seen that'when the contact-actuating bar 5 is released to the position shown in Fig. 4 of the drawings, the sprlng 15 is released to actuate the contact bar 4 out of engagement with the stationary contact 3.

In order that the contact bar 4 and the actuating bar 5 may be yieldingly held in operative positions relatively to each other, the lower end of the bar 5 is provided with a lug 17 that passes through an opening in the lower end of the contact bar 4. In order to prevent the bars 4 and 5 from turning on the bolt 11, the upstanding portion 12 of the switch support is provided with a laterallyextending flange 18.

The latch 6 is yieldingly secured to a support 19 that is secured to the base 1, by means of a bolt 20 and a coil spring 21, substantially as shown in Fig. 1 of the drawings. The end of` the latch 6 normally, presses against the bar 5 when the switch is in the circuit closing position, but if the latch 6`is moved upwardly, the end thereof engages an opening 22 in the bar 5 which permits the bar to be actuated to the left as shown in Fig. 4, in which position the switch mechanism is in open circuit position.

In order that the distance between the end of the latch 6 and the opening may be varied, (for a purpose to be hereinafter set forth), thel switch support 9 is provided with an adjusting member 23. The member 23 may be pivotally secured to the base by a bolt 24 that extends through the member 23, the switch support 9 and the base. A spring washer 25 is provided in order that the switch support may be frictionally held in the groove 10 of the base.

The movable member 23 is provided with a pin 26 that registers with an elongated opening 27 in the switch support 9. Thus, when the member 23 is moved either to the right or the left, the pin and the member 23 operate as a cam for actuating the switch support 9 longitudinally of the recess 10. If the handle member 23 istmoved inl a counter-clockwise direction, the switch-support 9 moves. upwardly in the recess 10, causing the opening 22 of the contact actuating bar 5 to be moved further away from the end of the latch 6. If the adjustimggfl member 23 is moved in a clockwise. direction, the switch support 9 is moved downwardly in the recess 10, causing the opening 22 to be moved closer to the end of the latch 6.

In order that the switch mechanism 2 may be actuated responsively to the current'traversing a three phase motor or other energy translating device (not shown), bimetallic strips 28 and 29 and resistors 31 and 32 are provided, the resistors being adapted to bew traversed by the phase currents of the motor or energy translating device.

Corresponding ends of the strips 28ans! 29 are secured to supporting lugs 33 and 34, of substantially L-shape,y mounted on the base 1. The other ends of the strips 28 and 29 engage a push rod 35 that extends laterally of the bimetallic strips and the upper end of which engages and actuates the latch 6 in accordance with the temperature of either one or both of the strips 28 and 29.

The resistors 31 and 32 are supported by terminals 36 and 37, respectively, that are mounted on the base 1. If the terminals 36 and 37 are connected in circuit with the phase windings of an electric motor or other energy translating device, the current traversing tne resistors 31 and 32 will cause the stri s 28 and 29 to be heated. Since the strips o bimetal lare alike, the ends of the strips will deflect upwardly, actuating the push rod 35 and the vlatch 6 until the end of the latch registers with the opening 22 in the contact actuating bar 5. When the latch is in this position, the .switch 2 is actuated to the open position as hereinbefore stated, and the energy-translating device controlled thereby deenergized.

The switch mechanism 2, the bimetal strips 28 and 29, the resistors 31 and 32, and the push rod 35 are shown and described in my Patent No. 1,725,518.

The value of current required to traverse the resistors 31 and 32, for a given period of time, in order to heat the strips 28 and 29 either individually or simultaneously to that temperature at which the end ofthe latch 6 will register with the opening 22 in the bar 5, is a function of the distance between the end of the latch and the opening. As hereinbefcne stated, this distance may be adjusted by the adjusting member 23. Generally stated, the greater the distance, the greater will be the current required to heat the bimetal strips to the temperature at which the switch will be actuated to its open circuit position, and the shorter the distance, the smaller will be the current required. f

In order that the switch 2 may be actuated to its closed position automatically, bimetal strips 38 and 39, to be heated by conduction from the resistors 31 and 32, respectively, are provided for actuating a push rod 41 downwardly, as the push rod 35 is moved upwardly.

The strips 38 and 39 are secured at one end to supports 42 and 43, respectively,'that are mounted on the base 1. The strips 38 and 39 are provided with laterally extending p0rtions 44 and 45 that are secured in direct contact with the resistors 31 and 32, respectively. Therefore, as the bimetal strips 28 and 29 are heated by the resistors 31 and 32, vthe 'strips 38 and 39 are heated accordingly, causing the push rod 41 to be moved downwardly a ainst the resistance of a spring 46, the spring eing disposed between the lower end' of the rod 41 and a lug 47 on the base.

When the push rod 41 has been moved downwardly, the bar 5 will be permitted to .move to the left the moment the end of the latch 6 enters the opening 22 of the Contact actuating bar 5. When the switch 2 has been actuated to its open circuit position and the resistors 31 and 32 have been deenergized, the

- bimetal strips 28 and 29 and 38 and 39 are cooled. Since they deflect in opposite directions, the rod 41 will be actuated upwardly tojengage an off-set portion 48 of the bar 5 and cause the switch 2 to be actuated to its circuit closing position (see Figs. 1 and 3).

The bimetallic elements 28 and 29 and the strips 38 and 39, together with the elements cooperating therewith as shown in the drawings, may be enclosed by a cover 49 of suitable material, in order to protect the elements from ambient conditions.

This `application of the thermal relay shown and described herein to electric motors is illustrated schematically in my Patent No. 1,725,518 therefore, it is thought unnecessary to describe the circuit connections involved in applying the relay of my present application to electric motors and similar devices.

While a specic embodiment'of the invention has been illustrated, it is to be understood that various modifications thereof may be ymade without departing from its spirit and scope. 'It is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

l. In a thermal relay in combination, a circuit interrupter biased toan open position, a pair of oppositely deflecting bimetallic members, a resilient member, and means for thermally energizing said bimetallic members, one of said bimetallic members being responsive to an increase in temperature to permit the circuit interrupter to be actuated from an initial circuit closing position to its open position, and the other of said bimetallic members being effective upon a decrease in temperature to permit the resilient member to actuate the circuit interrupter to its initial circuit closing position.

2. In combination, a circuit interrupter, means for opening the circuit interrupter, a .source of thermal energy, a bimetallic element responsive to said thermal energy for permitting the circuit interrupting means to actuate the circuit interrupter to its open position, aA second'bimetallic element disposed to deflect oppositely to the first bimetallic element responsive to said thermal energy and a resilient member associated with the second bimetallic element for returning the interrupter to a circuit closing position when said bimetallic members have cooled to a predetermined temperature.

3. In combination, a circuit interrupter, a bimetallic strip for actuating the interrupter from an initial circuit controlling position to another when heated to a temperature of a predetermined value, a resistor responsive to current fiow therethrough for heating said bimetallic strip, a resilient member and a second bimetallic strip responsive to the thermal energy of said resister for actuating the circuit interrupter to a circuit closing position .responsive to the cooling of said strips to a temperature of a predetermined Value.

4. In a control device, the combination with a circuit interrupter, and a source of supply of thermal energy, of means responsive to a predetermined thermal condition of said source of supply for actuating the interrupter to one circuit controlling position, and means including a resilient member and responsive to another thermal condition of said source of supply for actuating the interrupter to another circuit controlling position.

5. In a thermal relay, in combination, a. circuit interrupter spring biased to its open position, a resilient member and a plurality of thermally actuable means normally holding the circuit interrupter in its closed position and effective upon being heated to permit opening of the circuit interruptor, one of said thermally actuable means' being effective upon cooling to permit the resilient member to effect reclosing of the circuit interrupter.

6. In a thermal relay, in combination, a circuit interrupter spring biased to its open position, a plurality of latches for holding the circuit interrupter in its closed position during normal operating conditions, and a plurality of thermally actuable means for moving said latches to permit opening of said circuit interrupter under abnormal operating conditions, one of said latches being effective to reclose said circuit interrupterupon return of normal operating conditions.

7 In a thermal relay, in combination, a circuit interrupter spring biased to its open position, a plurality of thermally actuable latches for normally holding said circuit interrupter in its closed position and for permitting opening thereof, and resilient means operatively associated With the respective latches for returning them to their normal positions in Which the circuit interrupter is closed.

In testimony whereof, I have hereunto subscribed my name this 8th day of December, 1927.

CHARLES H. I-IODGKINS. 

